Special situation in intelligent network during which service provisioning fails but switching point operates successfully

ABSTRACT

A method associated with an intelligent network service, comprising the following steps for detecting a special situation and acting in the special situation in the best possible way: defining for the service at least one special situation which is failed for the service but successful for the switching point, defining an instruction for said at least one special situation, receiving at the detection point a message indicating the existence of the call-related service for which the special situation has been defined, receiving at the switching point a first routing instruction ( 201 ) either from a caller or the control point, checking said first routing instruction ( 203 ), detecting the special situation ( 204 ) if the first routing instruction includes the special situation, and following said instruction in response to the detection of the special situation. Besides the method, the invention also relates to an intelligent network, a service control point and a switching point of an intelligent network.

BACKGROUND OF THE INVENTION

The invention relates to services that are produced by means of anintelligent network and more particularly to services in which asituation that is failed for the service is successful for the actualnetwork.

An intelligent network (IN) is able to provide a subscriber of atelecommunications network, such as a wired network or a mobiletelephone network, with a plurality of various services. Such servicesinclude a virtual private network (VPN) which enables the use of privatenumbers, and a personal number in which the intelligent network reroutesthe calls directed to a personal number in a manner controlled by thesubscriber. An example of such an intelligent network is described inrecommendations of the International Telecommunications Union (ITU-T)Q-1200 series. In the following, the invention and its background willbe described by the terminology of recommendation ETS 300 374-1CoreINAP, but the invention can also be used in intelligent networksimplemented according to other intelligent network standards. Within thescope of the present application, the concept intelligent network alsorefers to other application platforms which provide similar types ofservices.

In the intelligent network, connection arrangements are separated fromservice control so as to provide intelligent network services which areindependent of the connection arrangements. The equipment or networkelement carrying out the tasks determined by a service control functionor service control functions (SCF) in the intelligent network is calleda service control point (SCP). Within the scope of the presentapplication, SCF and SCP are equal, and will hereinafter be called SCP.The SCP gives call set-up instructions to the exchange, or the exchangemay inquire call set-up instructions from the SCP. Exchanges responsiblefor an intelligent network interface are called service switching points(SSP). They contain at least a service switching function (SSF) and acall control function (CCF). The call control function CCF is not aservice associated with the intelligent network, but it is a standardfunction in exchanges, comprising high-level call handling functions ofan exchange, such as setting up and releasing transfer connections. Theservice switching function SSF is an interface between the call controlfunction CCF and the service control point SCP. Within the scope of thisinvention, the service switching point and the functional entity formedof the CCF and SSF are equal, and will hereinafter be called SSP.

In the conventional call set-up which takes place without the help ofthe intelligent network, telephone exchanges make independently alldeductions associated with call routing. In the intelligent network, theSCP also makes deductions associated with the routing. A basic callstate model (BCSM), defined in connection with the intelligent network,describes different phases of call control and includes the points atwhich the call control can be interrupted in order to start anintelligent network service. When the SSP detects that a call requiresan intelligent network service, it interrupts call processing andcontacts the service control point which invokes a logic programassociated with the service. Upon invocation of the logic program, aservice logic entity or service logic entities are created for the call,and their function determines the instructions which are transmitted bythe SCP to the SSP at each call phase. Service logic defines thedetection points in the call and connection process at which the servicelogic entities can have an interactive relationship with basic call andconnection control features. Call set-up or call release can betemporarily interrupted at the SSP at these detection points and furthercall handling instructions can be requested from the service controlpoint SCP. The SSP interprets the instructions obtained and starts therequired call control functions. If the service switching point SSPsucceeds in carrying out the functions according to the instruction itreceived, then call setup proceeds to the next phase, and no furtherinstructions concerning the previous phase are requested from the SCP.

It is a problem in the above arrangement that situations which arefailed for a service are successful for a switching point. In thesesituations the switching point continues call processing withoutrequesting additional instructions, although the situation failed forthe service. An example of such a service is a call list service, thepurpose of which is to reach the subscriber. However, the call may bedirected to a voice mailbox, in which case the situation is successfulfor the switching point but failed for the call list service.

BRIEF DESCRIPTION OF THE INVENTION

An object of the invention is to solve the above problem and provide amethod and equipment implementing the method so as to solve the aboveproblem. The objects of the invention are achieved by a method which ischaracterized by defining for the service at least one special situationduring which provisioning of the network service fails but the switchingpoint operates successfully, defining an instruction for said at leastone special situation, receiving at the detection point a messageindicating the existence of the call related service for which thespecial situation has been defined, receiving at the switching point afirst routing instruction either from a caller or the control point,checking said first routing instruction, detecting the special situationif the first routing instruction indicates the occurrence of the specialsituation, and following said instruction in response to the detectionof the special situation.

The invention further relates to a method which is characterized bydefining a special character by means of which the caller of the callthat activated the service is able to indicate a special situationduring-which provisioning of the call for the caller fails but theswitching point operates successfully, receiving the special characterat the switching point, detecting the special situation in response tothe received special character, requesting a second routing instructionin response to the detection of the special situation, and transferringcall control to the service control point.

The invention further relates to an intelligent network in which themethods of the invention can be applied. The intelligent network of theinvention is characterized in that at least one special situation isdefined for the service, it being failed for the service but successfulfor the switching point, an instruction has been defined for said atleast one special situation, and the service switching point is arrangedto detect the special situation and follow said instruction in responseto the special situation.

The invention further relates to a service switching point of anintelligent network, suitable for use in the methods and intelligentnetwork of the invention. The intelligent network service switchingpoint of the invention is characterized in that the switching pointincludes memory means for storing at least one definition for a specialsituation and its instruction for at least one service, the specialsituation being failed for the service but successful for the switchingpoint, checking means for checking if the received routing instructionleads to a special situation, and function means responsive to thechecking means for carrying out the operation of the instruction.

The invention further relates to a service control point of anintelligent network, suitable for use in the methods and intelligentnetwork of the invention. The intelligent network service control pointof the invention is characterized in that for a control point service isdefined at least one special situation during which provisioning of theservice fails but connection set-up is successful, the control pointincludes reception means for receiving a situation message indicatingthe special situation, and management means are arranged to give newconnection set-up instructions in response to the situation message.

The basic idea of the invention is to detect a service-related specialsituation and, as distinct from the prior art, to act in the specialsituation in a way that is suitable for the special situation and theservice, such as inquire the caller in connection with a call listservice if (s)he wishes her/his call to be connected to a voice mailbox.An advantage of this is that the service is able to influence the actionthat is taken in the special situation, whereby the objective of theservice is achieved in the best possible way.

In a preferred embodiment of the invention, a special situation isdetected not until a special character dialed by a caller is received.An advantage of this is that it also provides an opportunity to react tospecial situations on occasions in which the service switching point hasnot detected a special situation, because the voice mailbox is locatedin another exchange, for example, to which the switching point isconnected via a telephone network, and the switching point is thereforeunable to detect the special situation.

In a preferred embodiment of the invention, new instructions arerequested in a special situation. An advantage of this is that theservice gives further instructions by taking into account theinstructions obtained from a subscriber of the service, for instance.The service may even request instructions from the caller, even though(s)he would not be the subscriber of the service. The caller is thusable to decide if (s)he wishes to leave a message in the voice mailboxor if (s)he wishes to still try to reach the called party, i.e.subscriber B, for example.

In a preferred embodiment of the invention, the service control pointnotifies the switching point that checking the special situation is nolonger necessary. An advantage of this is that it is possible to changea service in the middle of a call to a service not having a specialsituation and to accept routing that leads to a special situation. Forexample, in the call list service routing to a voice mailbox is notaccepted until all other numbers have been gone through.

In a preferred embodiment of the invention, an instruction for a specialsituation is defined at the service switching point. Thus, unnecessarysignaling is avoided between the control point and the switching point.This is especially an advantage in special situations in which releasingthe connection is more meaningful for the service than routing the call.

The preferred embodiments of the methods, intelligent network, serviceswitching point and service control point of the invention are disclosedin the attached dependent claims.

LIST OF FIGURES

In the following, the invention will be described in more detail bymeans of preferred embodiments with reference to the accompanyingdrawings, in which

FIG. 1 illustrates a telecommunication system utilizing an intelligentnetwork,

FIG. 2 shows a flow diagram of a first preferred embodiment of theinvention,

FIG. 3 shows a flow diagram of a second preferred embodiment of theinvention,

FIG. 4 illustrates an intelligent network switching point of theinvention,

FIG. 5 illustrates an intelligent network control point of theinvention, and

FIGS. 6 and 7 illustrate exemplary signalings according to theinvention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a telecommunication system utilizing an intelligent networkIN. FIG. 1 shows elements and functions essential to intelligent networkservices. Network elements which comprise a service switching functionSSF and a call control function CCF are called service switching points.The call control function CCF is not a function associated with theintelligent network, but a standard function in exchanges, comprisinghigh-level call handling functions of an exchange, such as setting upand releasing transfer connections. The service switching function SSFis an interface between the call control function CCF and a servicecontrol function SCF. The SSF interprets requests transmitted by the SCFand forwards them to the CCF which invokes call control functionsrequired by them. Correspondingly, the call control function CCF usesthe SSF for requesting instructions from the SCF. The SSF is tightlycoupled to the CCF and functions as an interface for the CCF.Consequently, each SSF is located in the same exchange together with theCCF. The service switching point of the invention is described in moredetail in connection with FIG. 4. The service switching point SSP shownin FIG. 1 is a telephone exchange which includes, along with the CCF andthe SSF, a call control agent function (CCAF) providing users, i.e.callers A1, A2, with access to the network. Since the SSP includes theCCAF, the SSP may be a local exchange of a fixed network or a mobileservices switching centre which controls a base station subsystem BSS ofa mobile telephone network PLMN, for instance. The terminal of the usermay therefore be a telephone, a private branch with telephones or amobile station communication over an air interface and includingequipment supporting it.

Network elements which include the service control function SCF arecalled service control points SCP. The service control function is acentralized authority in the intelligent network and includes anexecution environment for service logic programs, for instance. Aservice logic program is invoked at the service control point SCP inconnection with an intelligent network service. The operation of theservice logic program determines the instructions which are transmittedto the SSP by the SCP at each phase of the call in messages, oroperations, between the service switching point and the service controlpoint. The service control point of the invention is described in moredetail in FIG. 5. The service control point SCP presented in FIG. 1 is asimplified version of the service control point, comprising only theservice control function SCF and the necessary interfaces.

A service data function (SDF) is a database used by the SCF. The servicelogic programs may inquire and update SDF data. For example,subscriber-specific or service-number-specific data can be stored in theSDF. The SDF may be either a database management system at the servicecontrol point SCP or it may be a separate service data point (SDP) asshown in FIG. 1, supporting an SCF-SDF interface and including adatabase DB.

A specialized resource function (SRF) of an intelligent network is aninterface for network mechanisms which are associated with interactionwith the subscriber. The SRF may be associated with intelligentperipherals (IP) as presented in FIG. 1 and it includes more advancedspeech handling functions than do the exchanges, or it may be located atthe service switching point SSP.

Several service switching points SSP may be connected to one servicecontrol point SCP and, correspondingly, one service switching point SSPmay be connected to several service control points SCP. For improvingthe reliability and dividing the load in the network, Several SCPs maycontain the same service logic program and data, or a connection to thesame data.

Some network nodes comprise a combined service switching point SSP andservice control point SCP. Such a network node is called a serviceswitching and control point (SSCP). It includes the functions of boththe SSP and the SCP and therefore produces similar services than do thecorresponding separate points together.

In the telecommunication system of FIG. 1, the network elements areconnected to one another via a signaling network SS7. Other networks,such as ISDN, can also be used.

FIG. 2 shows a flow diagram of a first preferred embodiment of theinvention at a service switching point SSP. In the first preferredembodiment of the invention it is assumed that instead of a call releasecommand, a routing command is obtained from a service control point. Inaddition, it is assumed that connection set-up is successful, i.e. thecall will be answered. A call list service is used as an example of aservice. A special situation defined for it is a situation in which thecall is routed to a voice mailbox (VMB) and an instruction in thespecial situation is defined to be to request a new routing instruction.The request for new routing instruction automatically transfers callcontrol from the switching point to the service control point. In thecall list service, a set of numbers are defined for subscriber B, i.e.for the called party, and an attempt is made to reach subscriber B bygoing through the numbers.

Referring to FIG. 2, the service switching point receives a routinginstruction B1 from the service control point in a Connect operation instep 201. In response to receiving the routing instruction B1, theservice switching point checks if the call list service is involved instep 202. The switching point may perform the checking from theinformation it received in the Connect operation, for example. TheConnect operation also containing information on the service, inaddition to the routing instruction, may include other information, suchas a notification that subscriber B has a call list service. If the SSPfinds out that the call list service is involved, the SSP checks, instep 203, if the number included in the routing instruction B1 is thenumber of the voice mailbox. The checking in step 203 is carried out bymeasures provided by the exchange, i.e. combination of at least the SSFand the CCF, and obvious to those skilled in the art, i.e. by analyzing,using parameter files, codes, and so on.

If the received routing instruction B1 includes the voice mailboxnumber, then the SSP detects a special situation in step 204, andrequest a new routing instruction from the SCP in step 205. The servicecontrol point gives a new routing instruction in accordance with servicelogic. If the service logic provides the call list service, the newrouting instruction may be an instruction which the SCP requested fromthe caller, i.e. subscriber A, or the next number in turn in the calllist. A routing instruction B2 is received at the service switchingpoint in step 206 in response the request sent in step 205. Next, it ischecked if the routing instruction B2 is the same as the routinginstruction B1 in step 207. If it is detected in step 207 that therouting instruction B2 is the same as the routing instruction B1, thecall is routed in step 208 and a connection is set up in step 209.Generally, if a Continue operation is received as a routing instructionin step 206, the same routing instruction has been received, and therouting proceeds in accordance with the received routing instruction instep 201.

If the routing instruction B2 is not the same as routing instruction B1,i.e. if a different number is involved, then the routine returns fromstep 207 back to step 203 to check if the number in the routinginstruction B2 is a voice mailbox number. Generally, if a Connectoperation is received as a routing instruction in step 206, then arouting instruction B2 is different than routing instruction B1.

If it is detected in step 203 that the voice mailbox number is notinvolved in routing instruction B2, the routine proceeds to step 208 toroute the call. The routine proceeds therefrom by setting up aconnection in step 209.

If in step 202 it is detected that the call list service is notinvolved, the routine proceeds to step 208 to route the call accordingto the routing instruction B1. The routine proceeds therefrom by settingup a connection in step 209.

In a first preferred embodiment of the invention, a special character isreceived from subscriber A at the service switching point uponconnection set-up in step 210. The special character is received becausethe voice mailbox is located in another exchange behind the telephonenetwork, for example, and the switching point cannot therefore recognizeit. In that case, the caller, i.e. subscriber A has received aninstruction in a welcoming message of the voice mailbox VMB, forexample, according to which the caller can attempt to reach the calledparty by dialing the special character upon reception of the message, incase the caller does not want to leave a voice message. The specialcharacter is so defined that the reception of the special characterleads to the detection of a special situation in step 211. Next, in step212 the connection is released from the service switching point to thepoint according to the routing instruction. The connection is maintainedfrom the service switching point to the caller, i.e. subscriber A. Inother words, the connection set-up in step 209 is released. A newrouting instruction is requested from the service control point in step213. The service control point gives a new routing instruction accordingto service logic. If the call list service is involved, the routinginstruction can be either an instruction requested from the caller, i.e.subscriber A or the next number in turn in the call list. A routinginstruction B3 is received in step 214, the call is routed in step 215and a connection is set-up in step 216. In another embodiment, theroutine may proceed from step 214 to step 207 and from there onwards asdescribed above.

The above embodiment and its alternatives can be divided into twoindependent embodiments, of which one or the other is used. Steps 201 to209 can be made into an independent embodiment as well as steps 208 to216.

In other embodiments, the checking of step 207 can be fully skipped andthe routine proceeds directly from step 206 to step 208.

FIG. 3 shows a flow diagram of a second preferred embodiment of theinvention at a service switching point SSP. It is also assumed thereinthat instead of giving a call release command, a service control pointgives routing instructions, and that connection set-up is successful,i.e. the call will be answered. Similarly, a call list service whichincludes a special situation of routing the call to the voice mailboxVMB and the corresponding instruction is used as an example of aservice.

Referring to FIG. 3, the service switching point receives a routinginstruction B1 from the service control point in a Connect operation instep 301 and routes the call in step 302. Next, the service switchingpoint checks if the call list service is involved in step 303. Theswitching point may be notified of the call list service in the Connectoperation, for example, which also transmits information on the service,in addition to the routing instruction. If the call list service isinvolved, it is checked if the number in the routing instruction is avoice mailbox number in step 304. The checking is carried out in themanner described in connection with FIG. 2. If the routing instructionincludes the voice mailbox number, then a special situation is detectedin step 305, the routing thereto is blocked in step 306 and a newrouting instruction is requested in step 307. The service control pointgives a new routing instruction according to service logic. If a voicelist service is involved, the routing instruction may be either aninstruction requested from the caller, i.e. subscriber A or the nextnumber in the call list. A routing instruction B2 is received at theservice switching point in step 308. Next, it is checked if the routinginstruction B2 is the same as the routing instruction B1 in step 308.Generally, if a Connect operation is received in step 308, a differentnumber is involved, and if a Continue operation is received in step 308,the routing proceeds according to the routing instruction received instep 301. If it is detected that the routing instruction is the same instep 309, then the call is released, since the routing thereto wasblocked in step 306. If a different number is involved, the routineproceeds from step 309 to step 310 to route the call, and the routineproceeds therefrom by setting up a connection in step 311. In otherembodiments, the routine may return from step 309 to step 304, if thenumbers in the routing instructions differ from each other.

If it is detected that the voice mailbox number is not involved in step304 or if it is detected that the call list service is not involved instep 303, the routine proceeds to step 310 to route the call andcontinues therefrom by setting up a connection in step 311.

In a preferred embodiment, it is checked if the call list service isinvolved after step 308. If so, the routine proceeds to step 309 andcontinues therefrom. Correspondingly, if the call list service is notinvolved, the routine proceeds directly to step 310 and continuestherefrom. In this embodiment, the control point may announce that thespecial situation is no longer checked either in a separate operation orin an operation comprising the routing instruction B2; in other words,the SCP can change the service type to ‘not a call list’ and, therefore,allow routing of any kind. An advantage of this is that the SCP is ableto change the detection instruction of a special situation by, e.g.,accepting the routing of the last number of the call list while goingthrough the call list.

Steps 210 to 216 of the embodiment presented in FIG. 2 could also beincluded in the embodiment presented in FIG. 3.

The flow diagrams presented above in FIGS. 2 and 3 illustrate theinvention. The principles described therein can also be used in servicesother than the call list services. The first routing instruction may bereceived from the caller, i.e., subscriber A, and include a number givenby the caller. The checks that are performed in FIGS. 2 and 3 and theirlocations in the flow diagram naturally depend on how the specialsituations have been defined and with which special situations thechecks are associated. The service can also be announced indirectly byarming a detection point for a special situation in aRequestReportBSCMEvent operation, for instance, the encounter of whichleads to a similar result. Although not illustrated in the figures, acall release command could also be received as a new routinginstruction. Upon requesting the instruction, call control istransferred to the service control point and, correspondingly, receptionof the routing instruction transfers call control back to the servicepoint in both FIGS. 2 and 3.

Although not illustrated in FIGS. 2 and 3, a call release command storedat the service switching point or a new routing instruction to which acall is always routed upon the detection of a special situation of aservice could also serve as an instruction for a special situation. Sucha routing instruction could be ‘route to a maintenance centre’ or ‘routeto a voice mailbox in a normal way’. In such instructions, there is noneed to transfer call control to the service control point; thereforecall control is maintained at the switching point all the time.

FIG. 4 illustrates a service switching point SSP and its functionsessential to the invention. The SSP can be implemented in conventionalexchanges, provided that the exchange is able to separate basic callcontrol from service control. The service switching point SSP includesan exchange terminal SSP-ET for receiving signaling from, andtransmitting signaling to, other network nodes, and an application partSSP-AP that controls the exchange terminal. The application part SSP-APincludes the actual functions of an exchange, i.e., the serviceswitching function SSF and the call control function CCF (potentiallytogether with the CCAF depending on the type of exchange). Thesefunctions are described in more detail in connection with FIG. 1.

The application part SSP-AP includes a call-specific, basic call statemodel (BCSM) which is described above in the general description, andfinite state model instances (SSF-FSM). When an intelligent networkservice is required, the call is provided with the SSF-FSM for a SCPconnection, the SSFFSM transmitting call handling instructions betweenthe BCSM and the SCP. Upon completion of provisioning the intelligentnetwork service, the SSF-FSM is terminated. The same basic call statemodel BCSM may require a new intelligent network service at some othercall set-up phase. In that case, the BCSM is provided with a new finitestate model instance SSF-FSM. The finite state model instances SSF-FSMsassociated with the calls may occur concurrently and asynchronously.

The application part SSP-AP includes a service switching managemententity (SSME) for executing the operations received from the intelligentnetwork service control point, responding to the operations andrequesting instructions. The service switching management entity SSMEincludes an SSME control (SSME-C) for maintaining a dialogue on behalfof the finite state model instances SSF-FSMs between other parts of theswitching point and other network nodes and functions of the intelligentnetwork, e.g., the service control point. The service switchingmanagement entity SSME is responsible for creating, activating andmaintaining the finite state model instances SSF-FSMs. The SSME-Cdirects the received operation to the correct instance and creates theinstance, if necessary.

In the first and second preferred embodiments of the invention, theapplication part SSP-AP includes a memory M for storing a service, adefinition for a special situation and an instruction associated withthe service. In addition, in the first preferred embodiment of theinvention, special characters are stored in the memory, the reception ofwhich leads to the detection of a special situation. The applicationpart SSP-AP of the switching point is responsible for the all of thetasks or some of the tasks described in connection with FIGS. 2 and 3,depending on the embodiment.

FIG. 5 illustrates a service control point SCP and its functionsessential to the invention. The SCP includes at least a terminal partSCP-ET for receiving signaling from, and transmitting signaling to,other network nodes, and an application part SCP-AP, which controls theterminal part.

The application part SCP-AP includes at least one service logic programSLP (which is used for producing intelligent network services and forwhich a special situation exists) and a service control function SCF(which is described in connection with FIG. 1). In addition, theapplication part SCPAP includes call state model instances (SCF SCSM).Specifically, each service request in the intelligent network creates acall state model instance SCSM according to the service logic programSLP. On behalf of the service logic program SLP, the SCSM maintains adialogue with the SSF, regarding the particular call service thatcreated the call state model instance SCSM. The call state modelinstances SCSMs associated with the call may occur concurrently andasynchronously. In addition, the application part SCP-AP includes aservice control management entity (SCME) with a SCME control (SCME-C)for transmitting operations to the service switching point. The SCME-Cis responsible for maintaining, in a centralized manner, dialoguebetween all call state model instances SCSMs associated with intelligentnetwork services and other parts of the control point and other networknodes in the intelligent network, e.g., the service switching point SSPand the service data function SDF. The SCME-C is responsible forcreating, activating and maintaining the call state model instancesSCSMs.

In the embodiments of the invention, the application part SCP-APincludes a software routine (not shown in the figure) which ensures thatthe SCSM is able to recognize the operation indicating a specialsituation, operate according to service logic and the special situationand give new routing instructions (which can also be releaseinstructions). In some embodiments, such as the first and the secondembodiments, the software routine also ensures that the SCSM includes(in the operation information) an indication that the service is aservice for which a special situation has been defined. In embodimentsin which the service logic expects that the checking of the specialsituation is finished before the checking of the next routinginstruction starts, the software routine ensures that information onthis is added either to an operation or is transmitted as a specificoperation.

FIG. 6 illustrates an exemplary signaling performed in accordance withthe invention. As illustrated in FIG. 6, the SCP contains definitions(6-1) for a call list service, the definitions including two specialsituation definitions with instructions. The first special situationrelates to a voice mail box (VMB); the corresponding instruction I-1 isto request a new routing instruction. The second special situationrelates to a special character #; the corresponding instruction I-2 isto release the connection and to request new routing information fromthe SCP.

Assuming that a caller wants to call subscriber B and dials his number,the SSP would then receive a call set-up request in message 6-2. At 6-3,the SSP would detect that the call set-up request relates to anintelligent network service IN. Therefore, the SSP sends message 64 tothe SCP requesting a routing instruction. The SCP then recognizes thatthe call list service is involved and sends, in message 6-5, a connectoperation including the above mentioned special situation definitionswith corresponding instructions to the SSP and a first routinginstruction B1.

From the content of message 6-5 , the SSP detects, at 6-6, that the callrelates to a network service for which at least one special situationhas been defined. The SSP then stores, at 6-6, the special situationdefinitions with their instructions and checks whether the numberincluded in the routing instruction B1 is a number of a voice mail box.In this example, the number is a number of a voice mail box in the samenetwork; therefore, the SSP detects, at 6-7, a special situation andcontinues according to the instructions relating to that specialsituation, i.e., instruction I-1.

According to the instruction I-1, the SSP requests new routinginstructions from the SCP in message 6-8. The SCP then sends a newrouting instruction B2 to the SSP in message 6-9. In response toreceiving message 6-9, the SSP checks again, at 6-10, whether the numberincluded in the routing instruction B2 is a number of a voice mail box.In this example, illustrated in FIG. 6, the SSP determines that therouting instruction B2 does not include such a number. Thus, the SSPthen checks, at 6-10, whether the routing instruction B2 contains thespecial character #.

In this example, the routing instruction B2 does not contain the specialcharacter. Therefore, the SSP routes the call according to routinginstruction B2 to a CB2 in message 6-11. In this example, the CB2 is avoice mail box located in another network. Therefore the SSP fails torecognize that routing instruction B2 contains a number of a voice mailbox. When the call is routed to the CB2, the CB2 plays a voice message6-12 to the caller. However, the caller is not satisfied and dials, at6-13, the special character # which is transmitted to the SSP in message6-14.

In response to receiving the special character #, the SSP detects, at6-15, the special situation and proceeds to operate in accordance withthe instruction I-2; according to instruction I-2, the SSP releases theconnection to the CB2 and requests new routing instructions from the SCPin message 6-16. The SCP then sends new routing instruction B3 to theSSP in message 6-17. In response to receiving message 6-17, the SSPchecks again, at 6-18, whether the number included in the routinginstruction B3 is a number of a voice mail box. In this example,illustrated in FIG. 6, the SSP finds out that the routing instruction B3does not include such a number. Subsequently, the SSP checks, at 6-18,whether the routing instruction B3 contains the special character #. Inthis example, the routing instruction B3 does not contain the specialcharacter. Therefore, the SSP then routes the call according to routinginstruction B3 to a CB3 in message 6-19. In this example, the subscriberB answers and a call is established between the subscriber B and thecaller.

FIG. 7 illustrates another exemplary signaling according to theinvention. As illustrated in FIG. 7, the SCP contains definitions (7-1)to a call list service, the definitions including one special situationdefinition with instructions. That special situation relates to aspecial character # and the corresponding instruction II-1 is to releasethe connection and to request a new routing information.

Supposing that a caller wants to call subscriber B and dials his number(as illustrated in FIG. 7), the SSP receives the call set-up request inmessage 7-2 and detects, at 7-3, that the call set-up request relates toan intelligent network service IN. Therefore, the SSP sends message 7-4requesting routing instruction to the SCP.

The SCP recognizes that the call list service is involved and sends, inmessage 7-5, a connect operation (including the special situationdefinition with instructions to the SSP) and a routing instruction toroute according to the routing instruction given by the caller.

The then SSP detects, at 7-6, from the content of message 7-5, that thecall relates to a network service for which at least one specialsituation has been defined; subsequently, the SSP stores, at 7-6, thespecial situation definition with its instructions and routes the callin message 7-7 to a CB1 according to the routing instruction given inmessage 7-2 by the caller.

In this example, when the call is routed to the CB1, a voice mail boxanswers and plays a voice message 7-8 to the caller. However, the calleris not satisfied and dials, at 7-9, the special character #, which istransmitted to the SSP in message 7-10. In response to receiving thespecial character#, the SSP detects, at 7-11, the special situation andcontinues according to the instruction II-1 (the SSP releases theconnection to the CB2 and requests new routing instructions from the SCPin message 7-12). The SCP then sends a new routing instruction to theSSP in message 7-13. In response to receiving message 7-13, the SSProutes, in message 7-14, the call to a CB3 according to routinginstruction in message 7-13. In this example, the subscriber B answersand a call is established between the subscriber B and the caller.

It is to be understood that the above description and the relatedfigures are only intended to illustrate the present invention. It willbe apparent to those skilled in the art that many variations andmodifications can be made to the invention without departing from thescope and spirit of the invention disclosed in the attached claims.

What is claimed is:
 1. A method of handling a special situationoccurring during provisioning of a network service, the method providingcall-related instructions to a service switching point of a network viaa service control point of the network, the method comprising: defining,for the network service, at least one special situation during whichprovisioning of the network service fails but the service switchingpoint successfully operates, defining an instruction for said at leastone special situation, receiving, at the service switching point, amessage indicating the existence of the network service for which thespecial situation has been defined, the network service relating to acall, receiving, at the service switching points a first routinginstruction, checking, in the service switching point, whether the firstrouting instruction indicates an occurrence of the special situation,detecting the special situation if the first routing instructionindicates the occurrence of the special situation, and following saidfirst routing instruction in response to the detection of the specialsituation.
 2. The method of claim 1, wherein said first routinginstruction comprises: requesting a second routing instruction inresponse to the detection of the special situation, and transferringcall control to the service control point.
 3. The method of claim 2,further comprising: receiving from the service control point-anotification indicating that checking the special situation is no longernecessary, receiving the second routing instruction, and routing thecall according to said second routing instruction.
 4. A method ofhandling an intelligent network service, the intelligent networkincluding a service control point and a service switching point, themethod comprising: connecting a call according to a first routinginstruction, defining a special character by means of which a caller ofthe call that invoked the network service can indicate a specialsituation during which provisioning of the call for the caller fails butthe service switching point successfully operates, receiving the specialcharacter at the service switching point, detecting in the serviceswitching point the special situation in response to the specialcharacter being received, requesting a second routing instruction inresponse to the detection of the special situation, and transferringcall control to the service control point.
 5. The method of claim 4,wherein, in response to the second routing instruction, a portion of theconnected call which originates from the service switching point isreleased, and call connection set-up is continued in accordance with thesecond routing instruction at the service switching point.
 6. A networkcomprising a service switching point for connecting the network to othertelecommunications networks and a service control point for producingservices in the network, wherein for a network service is defined atleast one special situation during which provisioning of the networkservice fails but the service switching point successfully operates, aninstruction has been defined for said at least one special situation,and the service switching point is arranged to detect the specialsituation and follow said instruction in response to the specialsituation.
 7. The network of claim 6, wherein the service control pointis arranged to notify the service switching point that the specialsituation has been defined for the network service.
 8. The network ofclaim 6, wherein the service switching point is arranged to detect thespecial situation in response to a character received from the terminalof a caller of a call that invoked the network service and to transfercall control to the service control point in response to the specialsituation.
 9. The network of claim 6, wherein the service control pointis arranged to notify the service switching point that the specialsituation of the network service is no longer monitored, and the serviceswitching point is arranged to interpret that the network service doesnot have a special situation in response to said notification.
 10. Aservice switching point of a network, comprising an interface to aservice control point of the network and to a public telecommunicationsnetwork, reception means for receiving instructions from the servicecontrol point, routing means for routing or releasing a call, memorymeans for storing at least one definition for a special situation andits instruction for at least one network service, the special situationduring which provisioning of the network service fails but the serviceswitching point successfully operates, checking means for checking if arouting instruction that is received from the service control point or acaller leads to the special situation, and function means responsive tothe checking means for carrying out an operation of the routinginstruction.
 11. The service switching point of claim 10, wherein saidrouting instruction comprises call control transfer to the servicecontrol point.
 12. The service switching point of claim 10, wherein saidrouting instruction includes call release.
 13. The service switchingpoint of claim 10, wherein said routing instruction includes a newrouting instruction.
 14. A service control point of a network,comprising connection means to a service switching point, managementmeans for controlling connection set-up of a call which uses a networkservice, transmission means for transmitting instructions and dialinformation requests to the service switching point, at least adefinition for the network service, the definition defining at least onespecial situation during which provisioning of the network service failsbut connection set-up is successful, and reception means for receiving asituation message indicating the special situation, wherein themanagement means are arranged to give new connection set-up instructionsin response to the situation message.
 15. The service control point ofclaim 14, wherein the management means are arranged to indicate to theservice switching point that a network service for which at least onespecial situation has been defined is associated with the call.
 16. Theservice control point of claim 14, wherein the special situation relatesto a connection already set up, and in response to the specialsituation, the management means are further arranged to give a releaseinstruction to a portion of the set-up connection that originates fromthe service switching point.